Is it possible to build a system monitor for the FD?
01-25-05, 10:35 AM
#1
RX-7 Bad Ass
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Is it possible to build a system monitor for the FD?
Hey everybody!
After having a leisurely read of the shop manual the other night (yes, I do actually sit down and read the shop manual - I've read it cover to cover more than once
) I noticed that there's a BIG feature of the FD that NO ONE has ever taken advantage of.
If you go through Section F (the engine control/fuel section) you'll see many references to the DT-S1000. This is a simple computer that Mazda dealerships (in theory) would have. It plugs into the diagnostic plug under the hood and into the cigarette lighter for power, you pop a disk in with the RX-7 software, and you can then do TONS of stuff.
It can monitor ALL the inputs/outputs to the ECU (like the PowerFC), do simulation tests (for example, switch various relays and solenoids on and off), and even monitor up to 8 inputs, like air temp, water temp, RPM, ignition timing, you name it.
If we could figure out how to get this functionality, this would be a MAJOR deal for helping to work on and troubleshoot these cars.
On a more easy note, there is also supposed to be a way to monitor various switches on the car with a special tester. Basically, you tell it which switch you want to monitor (clutch switch, neutral switch, etc.) and it will toggle a light on and off as you move the switch. Simple, but makes it easy to figure out if you've got a bad clutch switch, etc.
The switch monitor would likely be easy to make with simple electronic parts. Emulating the DT-S1000 would be VERY hard - I think it works off some sort of serial data stream from the ECU. It's likely inputting commands to the ECU and the ECU is outputting data - figuring out *what* those commands are and how to interpret the output would be VERY tricky.
But, we may be in luck with a few things. First, most all early '90s Mazdas used that same diagnostic connector, or at least very similar. Second, I believe auto makers are supposed to make available their diagnostic interfaces for companies that want to make aftermarket scan tools. Point #2 could possibly be a regulation that was passed later on or something, though.
Anyhow, I'm going to continue to Google and dig for more information. There has to be SOME way to take advantage of this. Seems a shame that it can do all this neat stuff, but all we can do is short the TEN and GRND connectors and watch a blinky light.
Dale
After having a leisurely read of the shop manual the other night (yes, I do actually sit down and read the shop manual - I've read it cover to cover more than once
) I noticed that there's a BIG feature of the FD that NO ONE has ever taken advantage of.If you go through Section F (the engine control/fuel section) you'll see many references to the DT-S1000. This is a simple computer that Mazda dealerships (in theory) would have. It plugs into the diagnostic plug under the hood and into the cigarette lighter for power, you pop a disk in with the RX-7 software, and you can then do TONS of stuff.
It can monitor ALL the inputs/outputs to the ECU (like the PowerFC), do simulation tests (for example, switch various relays and solenoids on and off), and even monitor up to 8 inputs, like air temp, water temp, RPM, ignition timing, you name it.
If we could figure out how to get this functionality, this would be a MAJOR deal for helping to work on and troubleshoot these cars.
On a more easy note, there is also supposed to be a way to monitor various switches on the car with a special tester. Basically, you tell it which switch you want to monitor (clutch switch, neutral switch, etc.) and it will toggle a light on and off as you move the switch. Simple, but makes it easy to figure out if you've got a bad clutch switch, etc.
The switch monitor would likely be easy to make with simple electronic parts. Emulating the DT-S1000 would be VERY hard - I think it works off some sort of serial data stream from the ECU. It's likely inputting commands to the ECU and the ECU is outputting data - figuring out *what* those commands are and how to interpret the output would be VERY tricky.
But, we may be in luck with a few things. First, most all early '90s Mazdas used that same diagnostic connector, or at least very similar. Second, I believe auto makers are supposed to make available their diagnostic interfaces for companies that want to make aftermarket scan tools. Point #2 could possibly be a regulation that was passed later on or something, though.
Anyhow, I'm going to continue to Google and dig for more information. There has to be SOME way to take advantage of this. Seems a shame that it can do all this neat stuff, but all we can do is short the TEN and GRND connectors and watch a blinky light
.Dale
01-25-05, 10:41 AM
#2
Ee / Cpe
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their are way to take advantages of the obd tool. However the dealership diagnostic reader is very expensive. (afaik)
some companys have made products like this for other platforms (ecutek deltadash for subarus)
that software runs about 300$ if im not mistaken.
This product would benefit the few stock guys out their, but everyone who mods this car puts in something like a haltech or a pfc. So this product wouldent be smart to manufacture for our cars since their is such a low volume market.
some companys have made products like this for other platforms (ecutek deltadash for subarus)
that software runs about 300$ if im not mistaken.
This product would benefit the few stock guys out their, but everyone who mods this car puts in something like a haltech or a pfc. So this product wouldent be smart to manufacture for our cars since their is such a low volume market.
01-25-05, 10:42 AM
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I bet the Snap-On diagonistic computer can do it. Of course, it is very expensive. I used to have one, but didn't have an FD at the time, so I never got to test a FD on it.
01-25-05, 10:48 AM
#5
RX-7 Bad Ass
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Well, some of the legwork has been done -
http://www.technosquareinc.com/MDM100Z.pdf
Techtom Japan has made a box called the MDM-100Z. It's most of what I'm thinking of - it plugs right in to the diagnostic port and shows TONS of information. Bad part is it's $430 - ouch! But, at least someone has made something like this.
I'm also wondering if there's an aftermarket US made scan tool that would do the trick. Some of the newer scan tools are VERY reasonably priced. It's just hard to find the older stuff, as there's TONS of OBD-II scan tools out there
Dale
http://www.technosquareinc.com/MDM100Z.pdf
Techtom Japan has made a box called the MDM-100Z. It's most of what I'm thinking of - it plugs right in to the diagnostic port and shows TONS of information. Bad part is it's $430 - ouch! But, at least someone has made something like this
.I'm also wondering if there's an aftermarket US made scan tool that would do the trick. Some of the newer scan tools are VERY reasonably priced. It's just hard to find the older stuff, as there's TONS of OBD-II scan tools out there
Dale
01-25-05, 11:20 AM
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I think the biggest limiting factor you'll run into is the price. If it gets near to a pfc or haltech, why wouldn't you just get the new computer because of all the things you can do with it?
It's a great idea, though. If it could be done reasonably, I'm sure some would take advantage of it.
It's a great idea, though. If it could be done reasonably, I'm sure some would take advantage of it.
01-25-05, 01:20 PM
#7
RX-7 Bad Ass
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Well, I don't plan on just working on my FD - I plan on working on many others down the road. This would be less of a thing to install in the car and more of a tool to use for diagnosis.
Soon I'm going to do some experimenting with the switch scanner thing. In theory, you jump the TEN and GRND and have a test light hooked up to another connector in the diagnostics box. Then, you activate each switch individually - as you do so, the light lights up for each one. Not super fancy, but pretty slick.
Dale
Soon I'm going to do some experimenting with the switch scanner thing. In theory, you jump the TEN and GRND and have a test light hooked up to another connector in the diagnostics box. Then, you activate each switch individually - as you do so, the light lights up for each one. Not super fancy, but pretty slick.
Dale
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01-25-05, 02:55 PM
#9
RX-7 Bad Ass
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Here's some info from the Big List from back in the day -
Date: Sat, 14 Feb 98 19:51:35 -0800 From: Andrew Ghali Subject: (rx7) [3] ECU interface
I have had my '93 Touring for about a month now, and it's time for me to learn how the thing works on the inside. So I got the workshop manual which showed me that the 13B-REW is quite a bit more complex than the plain 13B NA on my '87 SE. But the ECU appears to be far more useful than my '87 in its ability to interface with the outside world and reveal the operating state of the car. Unfortunately, the manual is not very informative on this matter. From the diagrams and the troubleshooting procedures, I see that there is something called the "DT-S1000" that is able to monitor and control the ECU. I don't even want to ask what Mazda wants for that little beauty. But the fact that it exists means that we can do the same thing ourselves. From the manual, I've narrowed the interface down to 2 or 3 signal lines, TEN and FEN, and possibly MEN. When TEN is pulled low, it is in self-test mode, MEN will indicate the sum of 8 possible signals in the car and FEN seems to "buzz" the error codes. When TEN is left floating (or tied to B+, I haven't tried it yet) MEN will indicate O2 status - I expect something similar to the GREEN light in the 86-87 models (possibly all 2nd gens). However, on page [F-18], FEN is drawn as bi-directional. Also, I am guessing that instead of tying TEN high, low, or floating (high), it could be a serial data input, or not. What I'd like to know is: how do I talk to the ECU; what protocol (HDLC, I2C, MAP, EIA-232E etc), signal level (I assume 5V), bit rate, and encoding (NRZ, biphase, screwy Mazda proprietary). Then, on top of the physical layer, what is the information protocol - how do I query, what can I query, what are the responses, what can I command? I'm guessing that it can't be terribly complex but without a DT-S1000 to spy on, I have no idea. Theoretically, by federal law, this kind of information must be available so that the aftermarket is not frozen out of the test & diagnosis business by unscrupulous car manufacturers. I wouldn't even know who to call in the great Mazda hierarchy - as if anyone in Mazda USA gives a damn about products they've already sold. And I don't speak Japanese. And is there a source for the male (plug) end of the funky diagnostic connector or will I have to shell out for a 49-F088-005 Harness Type-1 from Mazda? Based on previous experience, I would guess Mazda wants over $100 for a piece of cable with connectors on both ends. Is there anyone/any place that has this information? Or am I the first person to try this? Or is this just a really bad idea? It started out as an idea to implement a cheap boost gauge - just get the ECU to tell you what it is reading. Andrew
Dale
Date: Sat, 14 Feb 98 19:51:35 -0800 From: Andrew Ghali Subject: (rx7) [3] ECU interface
I have had my '93 Touring for about a month now, and it's time for me to learn how the thing works on the inside. So I got the workshop manual which showed me that the 13B-REW is quite a bit more complex than the plain 13B NA on my '87 SE. But the ECU appears to be far more useful than my '87 in its ability to interface with the outside world and reveal the operating state of the car. Unfortunately, the manual is not very informative on this matter. From the diagrams and the troubleshooting procedures, I see that there is something called the "DT-S1000" that is able to monitor and control the ECU. I don't even want to ask what Mazda wants for that little beauty. But the fact that it exists means that we can do the same thing ourselves. From the manual, I've narrowed the interface down to 2 or 3 signal lines, TEN and FEN, and possibly MEN. When TEN is pulled low, it is in self-test mode, MEN will indicate the sum of 8 possible signals in the car and FEN seems to "buzz" the error codes. When TEN is left floating (or tied to B+, I haven't tried it yet) MEN will indicate O2 status - I expect something similar to the GREEN light in the 86-87 models (possibly all 2nd gens). However, on page [F-18], FEN is drawn as bi-directional. Also, I am guessing that instead of tying TEN high, low, or floating (high), it could be a serial data input, or not. What I'd like to know is: how do I talk to the ECU; what protocol (HDLC, I2C, MAP, EIA-232E etc), signal level (I assume 5V), bit rate, and encoding (NRZ, biphase, screwy Mazda proprietary). Then, on top of the physical layer, what is the information protocol - how do I query, what can I query, what are the responses, what can I command? I'm guessing that it can't be terribly complex but without a DT-S1000 to spy on, I have no idea. Theoretically, by federal law, this kind of information must be available so that the aftermarket is not frozen out of the test & diagnosis business by unscrupulous car manufacturers. I wouldn't even know who to call in the great Mazda hierarchy - as if anyone in Mazda USA gives a damn about products they've already sold. And I don't speak Japanese. And is there a source for the male (plug) end of the funky diagnostic connector or will I have to shell out for a 49-F088-005 Harness Type-1 from Mazda? Based on previous experience, I would guess Mazda wants over $100 for a piece of cable with connectors on both ends. Is there anyone/any place that has this information? Or am I the first person to try this? Or is this just a really bad idea? It started out as an idea to implement a cheap boost gauge - just get the ECU to tell you what it is reading. Andrew
Dale
01-25-05, 04:21 PM
#11
RX-7 Bad Ass
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Been workin' Google all afternoon....
The ECU we have is actually similar to the Ford Probe's, from what I can gather. The system is called "MECS" in Probe-speak. The diagnostic connector looks IDENTICAL to ours, has the same labels for the pins (TEN, FP, GND, etc.) you name it.
Did find information on pulling ABS, auto tranny, and airbag codes, but it's pretty much what we've got now - jumper a wire, watch the blinky light.
Did find more on the switch diagnostic, and I might play around with that tonight with Mr. Multimeter.
Just seems with the VERY hardcore base of enthusiasts in the RX-7 community, that we can find enough EE's, software guys, etc. to figure out how to do this.
Dale
The ECU we have is actually similar to the Ford Probe's, from what I can gather. The system is called "MECS" in Probe-speak. The diagnostic connector looks IDENTICAL to ours, has the same labels for the pins (TEN, FP, GND, etc.) you name it.
Did find information on pulling ABS, auto tranny, and airbag codes, but it's pretty much what we've got now - jumper a wire, watch the blinky light.
Did find more on the switch diagnostic, and I might play around with that tonight with Mr. Multimeter.
Just seems with the VERY hardcore base of enthusiasts in the RX-7 community, that we can find enough EE's, software guys, etc. to figure out how to do this.
Dale
01-25-05, 04:36 PM
#12
I'm taking EE classes right now, and very interested in this project. I know a guy at a Toyota dealership who might know some guys at Mazda dealerships. I think that the user's manual for this DT-S1000 device would be very useful to our cause. I'll see what I can find out this week.
-s-
-s-
01-25-05, 04:42 PM
#13
It lookw like this is also used on other Mazdas, including the 262. That makes me feel more optomistic about our chances of finding a DT-S1000 at a Mazda dealer.
Altavista translation of http://www.cncar.com/jdwx/mazda/626_v6_2/A04/B32.htm , pardon the funky engrish...
How reads takes the breakdown code
1, how reads takes the breakdown code
(1) uses the reflectoscope reflector
a. When PCME (host computer) discovers when 感应元件 has the breakdown, the use special-purpose tests
The meter (49.H018 9A1,49.B019 or DT-S1000) inspects the reason. The technician also may use
In market general " scan " tool, the special-purpose reflectoscope reflector may take out from the PCME storage
Breakdown code. If simultaneously has the many breakdowns code, the most glitch code first outputs, next
In turn outputs according to from infancy to maturity the order.
DT-S1000 is one kind of belt soft small dish " the horse from reaches " the computer diagnosis special-purpose reflectoscope reflector.
Attention: PCME can continuously inspect 输入元件 whether has the breakdown, however PCME only can in
The diagnosis attachment " TEN " 端子 meets, the ignition lock opens in the latter three seconds time examines
Outputs the part whether has the breakdown.
b. 检查步骤
< Like chart >
Special-purpose reflectoscope reflector 连接图
(a) and switches off the ignition lock the preheating engine to the normal operating temperature.
(b) connects the system elects set at to the diagnosis place, the system choice to set to " 1 ", 测试开关
Sets to " SELF TEST " (from test).
(c) connects the reflectoscope reflector (SST 49 H018 9a1) to the system selector, chooses
The switch sets to " A ", turns on the ignition lock.
(d) opens the ignition lock latter 3 seconds sends " toot toot " the sound, on the inspection numeral display monitor is
Otherwise has " 88 " the demonstration.
(e) if does not have " 88 " to glitter, inspects the host relay, the electric current supplies electric circuit, the data
Transmission wiring.
(f) if " 88 " continues to glitter 20 seconds, and follows " toot toot the " sound, then inspects PCME
1f foot sum accumulator according to 线接头 between whether short-circuits. If has the necessity replaces PCME pays equal attention to 复以
Above step.
(g) reads takes the breakdown code.
Attention:
After completes the service, eliminates the breakdown code.
c. After service processing (eliminates PCME breakdown code)
(a) separates the storage battery cathode and steps on 刹车踏板 above 5 seconds, in order to eliminates PCME stores
Breakdown code information. Again meets the storage battery cathode.
(b) connects the special-purpose tool 重新检查, determines does not have breakdown code existence.
(2) not special-purpose reflectoscope reflector
< Like chart >
Diagnosis place chart
When 感应元件 and the functional element breaks down, PCME saves the breakdown code may pass
Crosses on the gauge board the breakdown indicating lamp demonstration.
Attention:
PCME unceasing monitor 感应元件, however it only can in diagnosis attachment " TEN "
The foot meets, opens in the ignition lock 3 seconds carries on the inspection to the functional element. If
The fruit has the many breakdowns, the small first appearance, arranges in turn.
a. 检查步骤
(a) is warm machine and switches off the ignition lock to the normal operating temperature.
(b) foot connects the good jumper wire in diagnosis place " TEN " and " GND the ".
(c) rotates the ignition lock to the ON position
(d after) if the breakdown indicating lamp shines 3 seconds extinguishes, also is not again bright, does not indicate
Has the breakdown code.
(e) if the breakdown indicating lamp is bright, then starts to glitter, then recording breakdown code.
After (f) records all breakdowns code, takes the jumper wire.
b. Breakdown code elimination
(a) separates the storage battery cathode and presses 刹车踏板 above 5 seconds mays then to eliminate PCME stores
Saves the breakdown code, then meets the storage battery cathode.
(b) causes the engine to locate the normal operating temperature, meets the cross line.
(c) turns on the vehicle spoon, confirms does not have breakdown code existence.
Altavista translation of http://www.cncar.com/jdwx/mazda/626_v6_2/A04/B32.htm , pardon the funky engrish...
How reads takes the breakdown code
1, how reads takes the breakdown code
(1) uses the reflectoscope reflector
a. When PCME (host computer) discovers when 感应元件 has the breakdown, the use special-purpose tests
The meter (49.H018 9A1,49.B019 or DT-S1000) inspects the reason. The technician also may use
In market general " scan " tool, the special-purpose reflectoscope reflector may take out from the PCME storage
Breakdown code. If simultaneously has the many breakdowns code, the most glitch code first outputs, next
In turn outputs according to from infancy to maturity the order.
DT-S1000 is one kind of belt soft small dish " the horse from reaches " the computer diagnosis special-purpose reflectoscope reflector.
Attention: PCME can continuously inspect 输入元件 whether has the breakdown, however PCME only can in
The diagnosis attachment " TEN " 端子 meets, the ignition lock opens in the latter three seconds time examines
Outputs the part whether has the breakdown.
b. 检查步骤
< Like chart >
Special-purpose reflectoscope reflector 连接图
(a) and switches off the ignition lock the preheating engine to the normal operating temperature.
(b) connects the system elects set at to the diagnosis place, the system choice to set to " 1 ", 测试开关
Sets to " SELF TEST " (from test).
(c) connects the reflectoscope reflector (SST 49 H018 9a1) to the system selector, chooses
The switch sets to " A ", turns on the ignition lock.
(d) opens the ignition lock latter 3 seconds sends " toot toot " the sound, on the inspection numeral display monitor is
Otherwise has " 88 " the demonstration.
(e) if does not have " 88 " to glitter, inspects the host relay, the electric current supplies electric circuit, the data
Transmission wiring.
(f) if " 88 " continues to glitter 20 seconds, and follows " toot toot the " sound, then inspects PCME
1f foot sum accumulator according to 线接头 between whether short-circuits. If has the necessity replaces PCME pays equal attention to 复以
Above step.
(g) reads takes the breakdown code.
Attention:
After completes the service, eliminates the breakdown code.
c. After service processing (eliminates PCME breakdown code)
(a) separates the storage battery cathode and steps on 刹车踏板 above 5 seconds, in order to eliminates PCME stores
Breakdown code information. Again meets the storage battery cathode.
(b) connects the special-purpose tool 重新检查, determines does not have breakdown code existence.
(2) not special-purpose reflectoscope reflector
< Like chart >
Diagnosis place chart
When 感应元件 and the functional element breaks down, PCME saves the breakdown code may pass
Crosses on the gauge board the breakdown indicating lamp demonstration.
Attention:
PCME unceasing monitor 感应元件, however it only can in diagnosis attachment " TEN "
The foot meets, opens in the ignition lock 3 seconds carries on the inspection to the functional element. If
The fruit has the many breakdowns, the small first appearance, arranges in turn.
a. 检查步骤
(a) is warm machine and switches off the ignition lock to the normal operating temperature.
(b) foot connects the good jumper wire in diagnosis place " TEN " and " GND the ".
(c) rotates the ignition lock to the ON position
(d after) if the breakdown indicating lamp shines 3 seconds extinguishes, also is not again bright, does not indicate
Has the breakdown code.
(e) if the breakdown indicating lamp is bright, then starts to glitter, then recording breakdown code.
After (f) records all breakdowns code, takes the jumper wire.
b. Breakdown code elimination
(a) separates the storage battery cathode and presses 刹车踏板 above 5 seconds mays then to eliminate PCME stores
Saves the breakdown code, then meets the storage battery cathode.
(b) causes the engine to locate the normal operating temperature, meets the cross line.
(c) turns on the vehicle spoon, confirms does not have breakdown code existence.
01-25-05, 04:51 PM
#15
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01-25-05, 05:00 PM
#16
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Originally Posted by chopstix
Before '96, pretty much every manufacturer used their own codes, cable interfaces, you name it to handle engine codes. The OBD-II standard made a standard interface for engine codes, standard connector, etc. That's also part of the reason there wasn't a '96 RX-7 in the US - Mazda would have had to develop the OBD-II interface for a rotary for a car they only sold 500 of in '95. Not cost effective.
Dale
01-25-05, 05:05 PM
#17
Originally Posted by chopstix
Our electrical system is from the 'dark ages,' so to speak... communicating with it might even be simple, but nobody really knows how to do it. From the looks of things, not many owners have tried.
-s-
01-25-05, 05:37 PM
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yea but a decent scanner like a genisys has the ability to hook up. you buy the obdI cable package and you can see the datastream ,though limited and not as nice as the obdII. gm's obdI data is actually pretty good for example. on mine i can see the tps coolant temp idle and a few others, o2 sensor etc. not nearly as indepth as the mazda unit.
01-26-05, 01:42 AM
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Hey great reasearchin' there, Dale! My miata has the same connector. I always assumed those diagnosis modules just counted the CEL flashes. 
We'll have to get a copy of the protocol specs or, at the very least, one of these Mazda scanners. I doubt the analyzer's manual will say anything beyond "push this button, push that button". I'm not expecting it to have schematics included, but maybe it's worth a look.
The protocol's physical layer is probably a farily simple serial TTL 5V unipolar NRZ (0's and 1's represented by 0v & 5v), like your source mentions. But once we're getting some 1's and 0's out of the ECU, it'll be a pain to partition them into groups of control and data bytes, if it's not using a standard protocol. Even if we figure out that we're getting a byte that represents, say, water temp, we'll have to map the digital values to scaled and meaningful temperature (or whatever) units.
Try grilling Mazda for the specs.
My miata has the same connector. I always assumed those diagnosis modules just counted the CEL flashes. We'll have to get a copy of the protocol specs or, at the very least, one of these Mazda scanners. I doubt the analyzer's manual will say anything beyond "push this button, push that button". I'm not expecting it to have schematics included, but maybe it's worth a look.
The protocol's physical layer is probably a farily simple serial TTL 5V unipolar NRZ (0's and 1's represented by 0v & 5v), like your source mentions. But once we're getting some 1's and 0's out of the ECU, it'll be a pain to partition them into groups of control and data bytes, if it's not using a standard protocol. Even if we figure out that we're getting a byte that represents, say, water temp, we'll have to map the digital values to scaled and meaningful temperature (or whatever) units.
Try grilling Mazda for the specs.
01-26-05, 09:30 AM
#20
RX-7 Bad Ass
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Did a little more playing with it last night.
First off, if you look at the diagnostic connector, you'll notice that the whole connector isn't populated - there are many empty sockets. I think they made a standard connector, then had some cars with some features used different pins and whatnot.
The big thing I figured out is there are only *THREE* wires in the plug that go to the ECU. TEN, MEN, and FEN. That's it. The data stream has to use those 3 wires - no other way around it. Most of the other wires are for other systems - 2 for cruise control, 2 for ABS, 2 for auto tranny (if you have an auto), 2 for the airbag, 2 ground wires (which both go to the same ground source, BTW), a switched battery voltage lead (it's from the EGI fuse), one for the cooling fans...that's most of them. There's also an ignition signal for hooking up an underhood tach - it's just shared off the yellow/blue wire going from the ECU to drive the stock tach.
I'm amazed that the ECU only has those 3 wires and that they're so multi-purpose. One of the wires (MEN, I think) lets you monitor the switches in the car and can also show O2 feedback. Not 100% sure how that works.
Yeah, we might have to try and get ahold of someone at Mazda to get the specs. I'm sure they're available somehow - I can't see code scanner makers sitting down and reverse-engineering the whole interface to make a code scanner.
The tricky part to making the hardware is whether or not it uses a relatively standard serial protocol and method, or something funky. Seems logical that it would be something standard - there's no sense reinventing the wheel.
Dale
First off, if you look at the diagnostic connector, you'll notice that the whole connector isn't populated - there are many empty sockets. I think they made a standard connector, then had some cars with some features used different pins and whatnot.
The big thing I figured out is there are only *THREE* wires in the plug that go to the ECU. TEN, MEN, and FEN. That's it. The data stream has to use those 3 wires - no other way around it. Most of the other wires are for other systems - 2 for cruise control, 2 for ABS, 2 for auto tranny (if you have an auto), 2 for the airbag, 2 ground wires (which both go to the same ground source, BTW), a switched battery voltage lead (it's from the EGI fuse), one for the cooling fans...that's most of them. There's also an ignition signal for hooking up an underhood tach - it's just shared off the yellow/blue wire going from the ECU to drive the stock tach.
I'm amazed that the ECU only has those 3 wires and that they're so multi-purpose. One of the wires (MEN, I think) lets you monitor the switches in the car and can also show O2 feedback. Not 100% sure how that works.
Yeah, we might have to try and get ahold of someone at Mazda to get the specs. I'm sure they're available somehow - I can't see code scanner makers sitting down and reverse-engineering the whole interface to make a code scanner.
The tricky part to making the hardware is whether or not it uses a relatively standard serial protocol and method, or something funky. Seems logical that it would be something standard - there's no sense reinventing the wheel.
Dale
01-31-05, 07:48 PM
#21
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Could someone post a decent pic of the diagnostic port connector?
I just sold my FD, but I have access to plenty if I need to play. I previously wrote a whole bunch of software to talk to the Apexi Power FC, but I'd love to get the same sort of data directly from the stock ECU via the diag port.
Can anyone confirm the connector is the same as used on Ford Probe? i.e. MECS (Mazda Electronic Control System)
I just sold my FD, but I have access to plenty if I need to play. I previously wrote a whole bunch of software to talk to the Apexi Power FC, but I'd love to get the same sort of data directly from the stock ECU via the diag port.
Can anyone confirm the connector is the same as used on Ford Probe? i.e. MECS (Mazda Electronic Control System)
01-31-05, 10:30 PM
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Having been a G.M. dealership drive-ability specialist since the first computer control system (GM) I view my 93 ECU as a very basic processor. You guys know that Mazda got a pass with the FD involving OBD1. 99% of all cars in that era were outfitted with OBD1, some even had a version of OBD2 for research and development data. These systems are not much different than old F.I. systems used in German cars of long ago just quicker. To set up an interface would be more software than hardware. I think its a nice idea and have set up some of my own real basic feed back LED'S. The truth is in the real world most systems well the overwhelming majority only see the tip of the iceberg and really can only send you to an area to be supported by hands on circuit testing. I would just love to see a data stream but for now without a standalone and good one we are left to using our brains to isolate the problem. Again I would love to use a scanner on my 93 it would make things more comfortable. John St John
02-01-05, 01:32 AM
#23
nakasaki, is this the connector you're looking for?
Here is a list of ISO / SAE articles that relate to communication standards: http://www.softing.com/de/ae/normen.htm
-s-
Here is a list of ISO / SAE articles that relate to communication standards: http://www.softing.com/de/ae/normen.htm
-s-
02-01-05, 04:43 AM
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Yes, that is a 17-pin MECS connector - the same as used on Ford Probes that have Mazda engines
On the Ford Probe the scan tool connects to just TEN and FEN and nothing else.
Having great difficulty in finding any information at all on the MECS protocol though. I'm guessing the TechTom guys might have disassembled the code on the stock ECU to decode the protocol :|
I've ordered this book - maybe it'll help a bit:
http://www.amazon.com/exec/obidos/IS...613960-2679349
On the Ford Probe the scan tool connects to just TEN and FEN and nothing else.
Having great difficulty in finding any information at all on the MECS protocol though. I'm guessing the TechTom guys might have disassembled the code on the stock ECU to decode the protocol :|
I've ordered this book - maybe it'll help a bit:
http://www.amazon.com/exec/obidos/IS...613960-2679349
02-01-05, 09:53 AM
#25
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Awesome finds, guys! I think Mazda used that same connector in pretty much all their early '90s vehicles. My car had a battery short out at some time in the past, and the diagnostic connector was "melty" - got one off a Miata at the junkyard, and swapped the pins out as well as the sticker for the "lid" of the box.
As I found out above, the only wires going to the ECU are MEN, TEN, and FEN - that's it.
Yeah, the trickiest part is figuring out the communcation protocol, commands that the ECU will expect, etc. I imagine Mazda might have available documentation on the protocol and interface - I still plan on calling Mazda and seeing if anyone there can help. Worth a call.
Dale
As I found out above, the only wires going to the ECU are MEN, TEN, and FEN - that's it.
Yeah, the trickiest part is figuring out the communcation protocol, commands that the ECU will expect, etc. I imagine Mazda might have available documentation on the protocol and interface - I still plan on calling Mazda and seeing if anyone there can help. Worth a call
.Dale